The present invention relates to a control method for stopping a train precisely at a target point.
A conventional train stopping control method using an automatic train control device (hereinafter referred to as "ATO" device), for stopping a train or similar vehicle may be described as follows:
(1) Position markers in the form of signal transmitters, are situated at preselected locations short of the target point for informing the vehicle of its position; PA0 (2) The vehicle determines its position in response to the signals from the position markers, and generates at least one decreasing velocity pattern (hereinafter referred to as "velocity pattern"); and PA0 (3) The velocity of the vehicle is controlled in conformance with the velocity pattern and stops at a target point.
A conventional controlling method for stopping a train which is arriving at a station, at a target point, is disclosed in U.S. Pat. No. 4,066,230, and will be discussed herein with reference to FIG. 1.
In FIG. 1, the ATO device (not shown) on a train destined for a station S, determines that the train has passed a point A by receipt of a signal from a first position marker.
In accordance with the detection signal, the ATO device generates a first velocity pattern V.sub.P1 which is to decelerate the train at a rate of 2.5 Km/h/sec from an initial velocity of, for example, 75 Km/h.
As the train runs further to arrive at a point B, the actual velocity of the train coincides with the first velocity pattern, so that the ATO device produces a brake command to decelerate the train in accordance with the first velocity pattern V.sub.P1. As the train which is being decelerated reaches a point C, the ATO device receives a signal from a second position marker and is informed of the arrival at the point C. The ATO device then produces a second velocity pattern V.sub.P2, in accordance with the detection signal, to decelerate the train at a rate of 1.5 Km/h/sec from an initial velocity of, for example, 15 Km/h. The ATO device is adapted to make a higher level selection, i.e., to select the one of higher level out of two velocity patterns V.sub.P1 and V.sub.P2. In consequence, the control is switched from the following control following the first velocity pattern to the following control of the second velocity pattern which is of the higher level. In consequence, the ATO device acts to decelerate the train in accordance with a velocity pattern V.sub.P2 and, as it reaches a point D in the vicinity of the target point E, it detects the arrival at the point D upon receipt of a signal from a third position marker located at the position D. Upon receipt of this signal, the ATO device issues a brake command to a train speed controller to stop the train at the target point.
Referring now to FIG. 2 showing a train stopping control unit of a conventional ATO device, a receiver 20 receives a signal from a position marker 10 and produces a position signal PS. This position signal PS is applied together with distance pulses .DELTA.S generated by a tacho-generator which is a detector for detecting the running distance of the vehicle to an arithmetic unit 40.
The arithmetic unit 40 has an initial velocity setter 41 and a deceleration rate setter 42 which produce, respectively, an initial velocity setting and a deceleration rate setting in accordance with the position signal PS derived from the receiver 20. The arithmetic unit 40 further has a distance pulse counter 43 which calculates the running distance from the distance pulses .DELTA.S derived from the tacho-generator 30 and the position signal PS. This calculated running distance is applied to a velocity pattern calculator 44.
An actual velocity calculator 46 calculates the actual velocity of the train in response to distance pulses .DELTA.S. The velocity pattern calculator 44 produces a velocity pattern signal in accordance with the calculated distance signal, an initial velocity setting signal and a deceleration rate setting signal which is conducted to a comparator 45 which produces a brake output as a control command C. Control command C is proportional to the difference between the velocity pattern and the actual velocity of the train. The velocity of the train is controlled in accordance with this command C.
In the conventional method for stopping a train, using more than one velocity pattern, the velocity pattern having a higher velocity level is followed. The train can be stopped precisely at the target point in a comfortable manner if the generation of the first velocity pattern is made correctly and adequately. However, if the initial velocity setter 41 fails to provide the initial velocity signal of the first velocity pattern correctly, or if the deceleration rate setter 42 fails to provide the deceleration rate setting signal of the first velocity pattern correctly, the first velocity pattern V.sub.P1A1 shown by a one-dot-and-dash line in FIG. 3 of a velocity pattern V.sub.P1A2 as shown by two-dots-and-dash line in FIG. 3 are formed. In such a case, the second velocity pattern V.sub.P2 does not take the higher level in relation to the first velocity pattern V.sub.P1A1 or V.sub.P2A2. Therefore, the stopping control is made to regulate the train velocity following up the first velocity pattern V.sub.P1A1 or V.sub.P1A2, rather than the second velocity pattern, so that the train runs too far over the target point as will be understood from FIG. 3.
A solution to the above-described problem of the prior art is disclosed in Japanese Patent Laid-open No. 59409/1977, in which the ATO device receives a position signal from a second or third position marker after the train has run into a predetermined stopping control region and, if the train velocity is higher than a predetermined velocity, actuates an emergency brake or maximum normal brake or, alternatively, actuates the brake in several steps in accordance with the velocity difference, thereby to prevent the train from over-running.
This control method can stop the train at a point near the target point even in the case of erroneous operation of the initial velocity setter or the deceleration rate setter, because the brake is used to forcibly stop the train. However, this method still cannot stop the train precisely at the target point, because the stopping distance is varied by weather or other conditions.